In order to convey a strip-like cast piece (slab) drawn out of a mould, a continuous casting installation is provided with a large number of rolls which rotate about respective axes perpendicular to a conveying direction and are arranged side by side in the conveying direction.
In such a continuous casting installation, in recent years, in order to provide measures against quality problems such as an internal crack, segregation, etc., of the cast piece, there has been a tendency to reduce the dimension of a roll pitch of the rolls. However, in this case, the outer diameter of the roll must be reduced, and therefore there is encountered a disadvantage that the strength of the roll is lowered. To cope with this, not only opposite axial end portions of the roll but also an intermediate portion thereof have been supported by bearings.
FIG. 4 is a cross-sectional view showing a cylindrical roller bearing device 110 used for supporting an intermediate portion of a roll 111. The roll 111 is a mallet type roll which has a shaft portion 121 to be supported by the cylindrical roller bearing device 110 and roll portions 122A, 122B disposed respectively at opposite axial sides of this shaft portion 121 and serving as portions for actually conveying a cast piece. The cylindrical roller bearing device 110 comprises a cylindrical roller bearing 112, and a bearing box 113 supporting the cylindrical roller bearing 112, and the cylindrical roller bearing 112 comprises an inner ring 114 for fitting on the shaft portion 121, an outer ring 115 disposed radially outwardly of this inner ring 114, and cylindrical rollers 116 disposed between the inner ring 114 and the outer ring 115. The inner ring 114 as well as the outer ring 115 is formed as a two-split bearing which is divided into two sections at a radial line. The bearing box 113 is also divided into two sections (113E, 113F) in an upward-downward direction, and one (upper) division section 113E serves also as part of the outer ring 115.
The roll 111 used in a continuous casting installation is expanded by heat from the cast piece, and therefore in order to absorb a thermal expansion of the roll 111, the cylindrical roller bearing device 110 is so constructed that the inner ring 114 and the outer ring 115 are movable relative to each other in an axial direction.
Specifically, ribs 114B are formed respectively at opposite axial sides of a raceway surface 114A of the inner ring 114, and the cylindrical rollers 116 are restrained by the ribs 114B from axial movement relative to the inner ring 114. On the one hand, a raceway surface 115A of the outer ring 115 is formed into a width larger than that of the cylindrical rollers 116, and therefore the cylindrical rollers 116 are movable on this raceway surface 115A in the axial direction. In order that the roll portions 122A, 122B, when moved in the axial direction, will not contact with axial side faces 113A, 113B of the bearing box 113, respectively, gaps a1, a2 are formed respectively between the side face 113A and the roll portion 122A and between the side face 113B and the roll portion 122B.
Incidentally, a continuous casting machine employing mallet type rolls is disclosed in the following Patent Literature 1.    Patent Literature 1: JP-UM-A-62-183953 Publication